import java.net.*;
import java.io.*;

public class Server
{

public static void main(String[] args)
{
    ServerSocket serverSocket;
    try
    {
        serverSocket = new ServerSocket(8888);
        System.out.println("******Waitting the Client******");
        Socket socket = serverSocket.accept();
        System.out.println("******Connectting******");
        InputStream is = socket.getInputStream();
        InputStreamReader isr = new InputStreamReader(is);
        BufferedReader br = new BufferedReader(isr);
        String info = null;
        while ((info = br.readLine()) != null)
        {
            System.out.println("I'm Server,the Client says: " + info);
        }
        socket.shutdownInput();
        OutputStream os=socket.getOutputStream();
        PrintWriter pw=new PrintWriter(os);
        pw.write("MyEclipseServer welcome you! ");
        pw.flush();
        socket.shutdownOutput();
        socket.close();
        br.close();
        isr.close();
        is.close();
        os.close();
        pw.close();
        serverSocket.close();
    } catch (IOException e)
    {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
 }
}

import java.net.*;
import java.io.*;

public class Client
{

public static void main(String[] args)
{
try
{
    Socket socket = new Socket("localhost", 8888);
    OutputStream os = socket.getOutputStream();
    PrintWriter pw = new PrintWriter(os);
    pw.write("user:EclipseClient,password：123456");
    pw.flush();
    socket.shutdownOutput();
    InputStream is = socket.getInputStream();
    BufferedReader br = new BufferedReader(new InputStreamReader(is));
    String info = null;
    while ((info = br.readLine()) != null)
    {
        System.out.println("I'm Client,the Server says: " + info);
    }
    socket.shutdownInput();
    socket.close();
    pw.close();
    os.close();
    br.close();
    is.close();

} catch (UnknownHostException e)
{
    // TODO Auto-generated catch block
    e.printStackTrace();
} catch (IOException e)
{
    // TODO Auto-generated catch block
    e.printStackTrace();
}
}

}

<< JLink`;
InstallJava[];

Clear[serverSocket, socket, br, pw, info];
serverSocket = JavaNew["java.net.ServerSocket", 8888];
Print["******Waitting the Client******"];
socket = serverSocket@accept[];
Print["******Connectting******"];
br = JavaNew["java.io.BufferedReader",
JavaNew["java.io.InputStreamReader", socket@getInputStream[]]];
While[UnsameQ[info = br@readLine[], Null],
Print["I'm Server,the Client says: " <> info]];
socket@shutdownInput[];
pw = JavaNew["java.io.PrintWriter", socket@getOutputStream[]];
pw@write["Welcome you! From MathematicaServer"];
pw@flush[];
socket@shutdownOutput[];
socket@close[];
br@close[];
pw@close[];
serverSocket@close[]

Clear[socket, pw, br, info]
socket = JavaNew["java.net.Socket", "localhost", 8888];
pw = JavaNew["java.io.PrintWriter", socket@getOutputStream[]];
pw@write["user:MathematicaClient,password：123456"];
pw@flush[];
socket@shutdownOutput[];
br = JavaNew["java.io.BufferedReader",
JavaNew["java.io.InputStreamReader", socket@getInputStream[]]];
While[UnsameQ[info = br@readLine[], Null],
Print["I'm Client,the Server says: " <> info]];
socket@shutdownInput[];
socket@close[];
br@close[];
pw@close[];